The present invention relates to a support structure for a suspension centrifuge, more specifically to such a centrifuge adapted for an intermittent operation, especially in the sugar industry. Such a centrifuge is equipped with a device for the automatic monitoring of the filling operation of the centrifuge. The centrifuge shaft is rotatably supported by radial and axial bearing means spaced from each other and held in a so called ball head arrangement.
Suspension centrifuges of different types are known in the art comprising devices for the determination or monitoring of the filling operation. Generally, such monitoring of the filling is accomplished by continuously measuring the weight increase of the centrifuge drum as the massecuite flows into the drum. When a predetermined weight value is reached, the flow of massecuite is shut off. For this purpose a centrifuge as disclosed in German Pat. No. 1,002,691 has been supported, in a manner varying from the manner described above so that the centrifuge is capable of making only vertical movements, whereby the vertical movement depends on the weight of the load of the centrifuge. The vertical movement is sensed by or supplied to an electrical or pneumatic switching member by means of an elastic plate. The switching member in turn controls the filling elements of the centrifuge such as a valve controlling the massecuite flow. The available vertical movements result only in very small deflections of said elastic plate which thus may cause an erroneous shut off. Thus, German Pat. No. 1,007,701 discloses an improved version of the centrifuge described above. In the improved version the deflection of the elastic plate is translated by lever means to provide an enlarged movement in response to the vertical displacement of the centrifuge. The enlarged movement is then used for actuating the switching means for the massecuite supply device.
With the just described devices it is relatively difficult to ascertain precisely the filling weight of a centrifuge. Thus, German Pat. No. 1,101,295 describes a further development in which the centrifuge drum is longitudinally displaceable along its rotational shaft and the relative variation of the centrifuge drum position relative to the drum shaft or relative to an adjustable reference point is employed for determining the filling weight of the centrifuge drum. In this prior art arrangement of the centrifuge the longitudinal displacement of the drum relative to the rotational shaft of the drum is accomplished by means of a guide bushing, which supports the drum, whereby the drum is additionally supported by a spring including a dumping mechanism. The dumping mechanism comprises a piston cylinder arrangement including throttling openings in the piston.
The just described centrifuge structure has the disadvantage that oscillatory motions of the drum on its shaft cannot be avoided. It is not possible to adjust the dumping mechanism of this arrangement in such a manner that the oscillatory movements are completely avoided. Such an adjustment is not possible, because it would falsify the weight measuring results, because the increased dampening causes a delay of the longitudinal movement of the centrifuge drum relative to the shaft. As a result, the relative position of the centrifuge drum on its shaft deviates more and more from the value which represents the weight of the massecuite if no dampening were employed at all. Furthermore, the known arrangement is rather expensive due to the structural elements required for accommodating the axial displacement of the centrifuge drum relative to its rotational shaft. These elements also make the arrangement trouble prone. In addition, it is practically not possible to employ the prior art arrangement in connection with larger drums having, for example, a filling capacity of about 1,000 kgs or more. The realization of the vertical drum displacement along its rotational shaft becomes more and more difficult with increasing filling capacities due to the forces which must be transmitted from the rotational shaft to the centrifuge drum.